Method for creating appendices that clearly reference the location of an object

ABSTRACT

To generate appendices which uniquely reference an object geographically, a tree of possible paths (A . . . E) is generated. The paths are evaluated in accordance with predefined criteria, which are suited for use as termination criteria, already at the time the paths are formed. Of the remaining paths, at least that one is coded as an appendix which best fulfills at least one of the criteria.

FIELD OF THE INVENTION

[0001] The present invention is directed to a method for generatingappendices which uniquely reference an object geographically.

BACKGROUND INFORMATION

[0002] Various methods are known for transmitting location-specificinformation, such as traffic messages. For example, in a TMC (trafficmessage channel), a location is transmitted on the basis of a locationcode. A geographic position and, thus, also a local allocation of themessage are first rendered using a location database in the receiver.For navigational purposes, digital road maps are used, in which theindividual objects are characterized by their geographic location and bytheir street connections. To transmit any location-specific informationat all to receivers which contain an appropriate database (receiverdatabase), a coding—also referred to as referencing—is carried out onthe basis of a geographic context. This referencing goes beyond thespecification of geographic data, since these data are not able toexclude ambiguities. There are, moreover, deviations in the databases,for example due to various manufacturers. Therefore, to describe allthese data, referencing appendices are discussed in the following.

[0003] German Published Patent Application Nos. 100 38 343.2, 100 09149.0, and 100 23 309.0 have proposed methods which provide for areliable referencing in systems having distributed geographic databases.Beyond the original objective of generating references among objectswhich are, in fact, present in two different databases, but are eachdescribed differently, the methods in the aforementioned patentapplications enable geographic objects to be navigably incorporated in adatabase where they originally had not been present. To this end, theobject, e.g., a parking garage, is supplemented by appendices, e.g., bythe geometry of an access road. On the receiver side, using patternrecognition, an at least partial map matching is achieved, geometriccomponents present on the object side and not in the database beingreentered, for example as access roads.

SUMMARY OF THE INVENTION

[0004] According to the present invention, appendices are generatedwhich uniquely reference objects geographically. Thus, it is possible toautomatically generate extensive POI (places of interest) databases, oreven an “on-the-fly referencing”.

[0005] In contrast to the methods in the aforementioned patentapplications, the appendices, which are to be uniquely assigned to anobject, do not have to be selected manually, but rather can be selectedin accordance with a reliable automatic process which may be carriedout, in particular, on the basis of vector maps. When the paths forreferencing the objects are generated, criteria are used to evaluate andselect a path. These may be termination criteria, in those cases, forexample, where the object cannot be approached directly because of thepredefined driving direction within the path (one-way street). Besidesthese criteria, other criteria may also be provided to select that pathwhich best fulfills at least one of the criteria, i.e., is the mostprobable path.

[0006] In accordance with another exemplary embodiment, coordinatechains are used as paths, which lie at least partially on trafficroutes, which are contained in a receiver database and includecharacteristic properties of parts of a traffic route network.

[0007] Vector maps may be used as a basis for selecting the paths. Otherdata material pertaining to geographic objects and travel paths, e.g.,printed map material may be prepared in advance in vector maps.

[0008] According to a further exemplary embodiment, a few criteria forgenerating the appendices may be applied individually or in combination.

[0009] Several termination criteria may be used. Since these terminationcriteria are already applied when generating the paths, pathalternatives, which are not able to be implemented or are not uniqueenough, are excluded early on. Therefore, such excluded pathalternatives do not encumber the treelike path generation from theobject.

[0010] There are also several criteria for determining the geometricuniqueness when generating paths and, thus, the appendices.

[0011] By scaling the criteria, the receiver database may be adjusted tothe database to be generated, or the receiver database may be completelyset up in accordance with the requirements of the receiver (user), e.g.,in terms of resolution, object selection, etc.

[0012] The scaling may be dynamically carried out in an iterativeprocess.

[0013] In systems in which information of the aforementioned type iscoded online, in response to a customer query, the test for a clearcorrelation maximum may be performed not only in the generatingdatabase, but also be extended to the receiver (customer) database or beshifted there. This makes it possible, for example, to adjust theroad-classification range to be covered, thus to scale it in the senseof a standard scale and thereby optimize it.

[0014] The referencing of a path and, thus, of an appendix is carriedout to the point where a predefined representative of an object classknown to the receiver database is reached. It is thus assured that thereferencing of an object is carried out in any case to the point where alink to the traffic network stored by the user is reached.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015]FIG. 1 shows an example of a path selection for a parking garageto be referenced according to the present invention.

[0016]FIG. 2 shows an example transmission of appendices from agenerating database to a receiver database according to the presentinvention.

DETAILED DESCRIPTION

[0017] As FIG. 1 shows, a tree of possible paths A through E isgenerated, starting out from an object 20, e.g., a parking garage. Inthis context, the actual object 20 is supplemented by at least oneappendix which describes the geometry of the access road, which may bepresent in the receiver database and have a geometric form which isunique in the region being considered. The topology shown in FIG. 1 hasthree different road classes. Partial path 1 (thinnest line drawn),i.e., the direct access to the parking garage, is the road or streethaving the lowest classification. It is generally not found on anyready-made map and, in any case, appears in the appendix, since thereare no alternatives. Partial paths 2, 3, 4, 5, 6, 7 (medium lines drawn)are, in part, alternative roads/streets and belong to the middleclassification. The partial paths 8, 9 and 10 are the roads or streetsof the road or street network having the highest classification (thicklines drawn). They may appear completely both in the generatingdatabase, as well as in the receiver database and are, therefore,selected as preferred partial paths and coded in the appendix. Thefollowing may be selected as criteria for evaluating and selecting thepaths/partial paths in generating appendices which uniquely reference anobject geographically:

[0018] whether they lead out from object 20, from a road or streetnetwork having a low classification into one having a highclassification;

[0019] whether they have a unique geometry in the nearby geographicsurroundings;

[0020] whether from a technical navigational standpoint, they representa real path (passability, one-way streets, etc.) toward object 20 and/oraway from the object;

[0021] whether in terms of efficiency, they have a small length to becoded, so that, particularly with respect to the transmission andreceiver-side decoding, they may be processed without entailingsubstantial outlay.

[0022] When generating the logical tree of potential paths emanatingfrom object 20, predefined termination criteria are applied, such as thefollowing:

[0023] return path to a street having a lower classification than thecurrent one;

[0024] directional information indicating the object (one-way street) iswithdrawn, since, in any case, an access should be possible.

[0025] The paths are sorted and selected in accordance with theaforementioned criteria, and at least one path is coded as an appendix,which best fulfills at least one of the aforementioned criteria, as wellas, optionally, at least one additional criteria, which may be one ofthe aforementioned criteria, i.e., which represents a clear correlationmaximum. In this context, as paths, coordinate chains are used which lieat least partially on traffic routes, which are contained in a receiverdatabase 30 and include characteristic properties of parts of a trafficroute network.

[0026] To determine the geometric uniqueness, the following criteria maybe evaluated, both for the entire path, as well as successively duringset-up, or for partial paths (by street classification):

[0027] whether the sum of the amounts of the (relative) angular changesover the path/partial path exceeds a predefined limiting value;

[0028] using the least squares method, whether point sets belong to asame classification or street. For this, a set of form factors may begenerated via a non-linear coordinate transformation, for example inaccordance with German Published Patent Document No. 198 60 679.

[0029] by way of an optionally repeated geometric comparison, whether afound path conforms with a path in a generating database 40, i.e., aclear correlation maximum is ascertained.

[0030] By scaling the aforementioned criteria, an adaptation to the datain the receiver database may be undertaken. Through this measure, aselection specially tailored to the requirements of the receiver (user)may be made with respect to resolution, object selection, depth ofdetail, etc. The scaling may also be dynamically carried out in aniterative process. The customer's requirements are then progressivelymet as the database grows.

[0031] In systems in which geographical referencing information is codedonline, i.e., in response to customer queries, the test for a clearcorrelation maximum may also be expanded and/or shifted to the receiverdatabase. In this way, it is possible to adjust the road-classificationrange to be covered, thus to scale it in the sense of a standard scaleand thereby optimize it.

[0032] In the case of the example illustrated in FIG. 1, the parkinggarage—object 20—may be coded in the following manner:

[0033] start with object 20;

[0034] set up the tree emanating from object 20 (incompletely) and theresultant paths. Here, the termination criteria are: 1) return to thestreet having a lower classification than the current one; and 2)navigability to object 20.

[0035] This yields the following paths A through E:

[0036] A) partial paths 1 2 3

[0037] B) partial paths 1 4 7 8 9 10

[0038] C) partial paths 1 4 6 10

[0039] D) partial paths 1 4 6 9

[0040] E) partial paths 1 4 6 9 8.

[0041] The formation of paths using partial path 5 was ruled out bytermination criteria, since the one-way street (marked by directionalarrow) leads away from the object.

[0042] At this point, an appropriate appendix is selected in thefollowing manner: provided that the most highly classified streetclassification, shown in FIG. 1 with the thickest lines drawn (partialpaths 8, 9, 10), is at least present in receiver database 30 and, thus,in any case should constitute part of the appendix, then path A isdropped. Path C loses against paths B, D and E, since, in terms of thestreet classification, there is least geometric uniqueness. This alsoholds for D; after that follows path E. Given the required uniqueness,path B is to be coded as an appendix in the most highly classifiedstreet classification. In the individual case, of course, another orfurther appendices may also be coded, particularly when they best meetvarious criteria. It is especially practical to code two or moreappendices when various map material is to be taken as a basis, forexample when a set of appendices is to be used on receiver databaseswhich differ in terms of their depth of detail or in the classificationof the points of interest. This means that a user may effectively useappendices 50 transmitted from the generating database 40 to his/herreceiver database 30 in a manner that is tailored to his/herrequirements (FIG. 2).

[0043] To evaluate the paths and for preparation purposes, i.e., codingof the appendices, vector maps in which the details are digitallyavailable are particularly suited. For other map material includingprinted maps, a previous conversion into vector maps is performed.

[0044] An appendix from object 20 may be referenced such that the treefrom the path is extended to the point where a predefined representativeof an object class known to receiver database 30 is reached in any case.For this, generating database 40 retrieves the depth of detail of thereceiver database at least partially. In the previously introducedexample this would mean that, starting from object 20 (a parking garage)a probable path and, thus, an appendix, is referenced to the point wherea most highly classified street (representative of the object class) isreached which is assumed to be present in the receiver database. Thepaths may then be weighted, of course, in the previously describedmanner.

[0045] Another example of such a referencing would be when a receiverhas all the (main) train stations in his/her receiver database 30 as anobject class and requests that a referencing appendix from the object tobe referenced end at a (main) train station because this would ensureaccessibility to the receiver's traffic network.

What is claimed is:
 1. A method for generating appendices which uniquelyreference an object geographically, comprising the following features:starting out from object (20), a tree of possible paths (A . . . E) isgenerated; these paths (A . . . E) are evaluated in accordance withpredefined criteria, which are suited for use as termination criteria,already at the time the paths are formed; of the remaining paths (A . .. E), that one is coded as an appendix of the object (2) which bestfulfills at least one of the criteria, as well as optionally at leastone of other criteria.
 2. The method as recited in claim 1, wherein, aspaths (A . . . E), coordinate chains are used which lie at leastpartially on traffic routes, which are contained in a receiver database(30) and include characteristic properties of parts of a traffic routenetwork.
 3. The method as recited in claim 1 or 2, wherein, as a basisfor selecting the paths, vector maps are used, and other data materialpertaining to geographic objects and routes, including printed mapmaterial, is prepared in advance in the form of vector maps.
 4. Themethod as recited in one of claims 1 through 3, wherein, to generate theappendices, criteria are used, which lead individually or in acombination of at least two such criteria, to the following appendices:they lead out from object (20), from a road or street network having alow classification into one having a higher classification; they have aunique geometry in the nearby geographic surroundings; from anavigational standpoint, they represent a real path toward the object(20) and/or away from the object; they have a small length to be coded.5. The method as recited in one of claims 1 through 4, wherein thefollowing factual situations are used as termination criteria: returnpath to a street having a lower classification; directionalspecification does not indicate the object (20).
 6. The method asrecited in claim 4 or 5, wherein, to determine the geometric uniqueness,at least one of the following criteria is evaluated, both for the entirepath, as well as successively during set-up, or for partial paths: it isanalyzed whether the sum of the amounts of the angular changes over thepath exceeds a predefined limiting value; using the least squaresmethod, it is analyzed whether point sets belong to a sameclassification or street; by way of a geometric comparison, it isanalyzed whether a found path conforms with a path in a generatingdatabase (40), i.e., a clear correlation maximum is ascertained.
 7. Themethod as recited in one of claims 1 through 6, wherein theaforementioned criteria are scaled, in particular in accordance with therequirements of the receiver database (30).
 8. The method as recited inclaim 7, wherein the scaling is dynamically carried out in an iterativeprocess.
 9. The method as recited in one of claims 6 through 8, whereinthe correlation maximum is not only determined in the generatingdatabase (40), but is also expanded and/or shifted to the receiverdatabase (30).
 10. The method as recited in one of claims 1 through 9,wherein an appendix is referenced from the referencing object (20) tothe point where a predefined representative of an object class known toa/the receiver database (30) is reached.